Internal combustion engine of the fuel injection type having means for reducing the emission of unburned products with the exhaust gases

ABSTRACT

For an internal combustion engine of the fuel injection type, improved means are disclosed, aiming at reducing the emission of an unburned fraction in the exhaust gases, so as to diminish the causes of pollution of the atmosphere. According to the improvement, fuel feed cut-off means and air feed cut-off means are provided to cut off both the fuel feed and the air feed when the conventional fuel feed regulating means and air throttling means are in &#39;&#39;&#39;&#39;idling&#39;&#39;&#39;&#39; position and the engine speed is higher than the idling speed.

United States Patent 1191 1111 3,906,909

Garcea Sept. 23, 1975 15 INTERNAL COMBUSTION ENGINE OF THE 2,741,2334/1956 McKinley 123/97 B FUEL INJECTION TYPE HAVING MEANS 53:2 :26 3; h8

, ennesson FOR REDUCING THE EMISSION F 3,463,130 8/1969 Reichardt 61 al123/97 B UNBURNED PRODUCTS WITH THE 3,517,653 6/1970 Arigu et al. 123/97B EXHAUST GASES 3,570,460 4/1971 Rabus 123/97 B 3,670,706 6/1972Fujisawu 123/97 B [75] Inventor Gama Italy 3,688,752 9/1972 Baudry123/97 B [73] Assignee: Alfa Romeo, S.p.A., Milan, Italy 3,727,5914/1973 Sudo 123/97 B 3,795,237 3/1974 Denton 123/97 B [22] F11ed: Dec.14, 1973 [21] Appl. No.; 424,738 Primary ExaminerCharles J. MyhreAssistant ExaminerDavid D. Reynolds Related Application Data Attorney,Agent, or Firml-lolman & Stern [63] Continuation-impart of Ser. No.191,453, Oct. 21,

a 57 ABSTRACT [30] Foreign Application Priority Data For an internalcombustion engine of the fuel injection 061. 24, 1970 Italy 7344/70type, improved means are disclosed aiming at reducing the emission of anunburned fraction in the ex- 52 123 97 123/119 [23/139 AW haust gases,so as to diminish the causes of pollution [51] Int. Cl. F02D 31/00 ofthe atmosphere- According to the improvement 3 Field of Search ]23/97 B,1 19 A, 139 w fuel feed cut-off means and air feed cut-off means areprovided to cut off both the fuel feed and the air feed [56] ReferencesCited when the conventional fuel feecl regulating means and UNITEDSTATES PATENTS air throttling means are in idling position and the 2 395748 2/1946 M 23/97 B engine speed is higher than the idling speed.

a ory 2,506,511 5/1950 Mallory 123/97 B 3 Claims, 2 Drawing Figures 1 n//l' /l 1 1 1 I i 1 15 I 2 1 l D 36 1 I11 29 45 U will-{11f INTERNALCOMBUSTION ENGINE OF THE FUEL INJECTION TYPE HAVING MEANS FOR REDUCINGTHE EMISSION OF UNBURNED PRODUCTS WITH THE EXHAUST GASES RELATEDAPPLICATION This is a continuation in part application of my earlierapplication Ser. No. 191,453, now abandoned, filed Oct. 21, I971.

BACKGROUND OF THE INVENTION One of the most significant factorscontributing towards air pollution and, more particularly in inhabitedareas, is the emission, by internal combustion engines of motorvehicles, of exhaust gases which contain a not negligible fraction ofunburned products.

It has been shown that a significant fractionof the unburned products isemitted by an engine when the latter is driven to rotation by thetransmission unit, thus giving a negative torque: this phenomenonoccurs, in actual practice, whenever the driver releases the acceleratorpedal, thus closing the throttle and the engine, ,as connected to thevehicle wheels, .is driven to rotation at a rate which exceeds the oneattendant to it as a function of the air gasoline mixture drawn into theengine; the resultant braking action is resorted to for decelerating thevehicle run, or to prevent it from accelerating, as it occurs when thevehicle is descending a slope.

It is known that in an engine which is driven at a comparatively highspeed when the accelerator pedal is released, carburation difficultiesare experienced, due to the high negative pressure obtaining downstreamof the throttle and of the small rates of flow of both air and gasolineconcerned: in addition, combustion difficulties are also originatedinasmuch as the comparative rarefaction of the mixture encourages thephenomenon of extinction of the flame in the neighborhood of thecombustion chamber walls. These phenomena, along with others, areresponsible for a considerable percentage of unburned fractions in theexhaust gases.

In order to limit the emission of unburned fractions, in internalcombustion engines of the fuel injection type, it has been suggested toadopt devices which cut off the fuel injection to the engine when thelatter is driven by the vehicle wheels: this approach has the defeetthat the gases coming from the oil sump, which is connected to the airsuction duct, do not burn and thus soil the interior of the cylindersand are discharged into the atmosphere: a further, but not less seriousdrawback is that the air drawn into and exhausted from the cylinder, ifno combustion takes place, cools the cylinder walls, with the resultbeing difficulties in the combustion and an increase of the emission ofunburned fractions whenever the released accelerator pedal is depressedagain.

OBJECTS AND SUMMARY OF THE INVENTION An object of the present inventionis to reduce the emission of unburned fractions in the exhaust gases ofan internal combustion engine of the fuel injection type which is drivento rotation at a rather high rate and with the throttle placed in theidling position.

An additional object of this invention is to render particularly highthe braking torque supplied by the engine when the accelerator pedal isreleased.

According to the invention, an internal combustion engine of the fuelinjection type is provided, which comprises a combustion chamber, anintake duct leading to said chamber, fuel injecting means located insaid intake duct, fuel feed means connected to said fuel injectingmeans, regulating means coupled to said fuel feed means to regulate thefuel. feed, air feed means introducing air in the intake duct upstreamto the fuel injecting means, throttling means coupled to said air feedmeans to regulate the air feed concurrently with the operation of saidregulating means, fuel feed cut-off means, air feed cut-off means andcontrol means responsive to the concurrent operation of said regulatingmeans and said throttling means and to the engine speed to actuate thefuel feed and air feed cut-off means to cut-off the fuel feed and theair feed when said regulating means and said throttling means arearranged to regulate the fuel feed and the air feed' at the idlingvalues and the engine speed is higher than the idling speed.

Otherwise stated, according to the present invention both the fuel feedand the air feed are cut off when the engine is driven by the vehiclewheels, so that the above mentioned drawbacks encountered in the fuelinjection engines which are only provided with fuel feed cut-off meansare thus eliminated and. a relevant reduction of unburned fractions inthe exhaust gases is obtained.

In order that the present invention may be better understood, twoexemplary embodiments thereof will now be described and diagrammaticallyshown in the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatical view,partly in section, of an exemplary embodiment of the invention, and

FIG. 2 is a view, similar to FIG. 1, of an alternative exemplaryembodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS As appears in FIG. 1, aninternal combustion engine of the fuel injection type has a combustionchamber 14, an exhaust duct 15 and an intake duct 13, which communicateswith a manifold 12, where other intake ducts of every cylinder may open,according to a well known diagram. An air intake pipe,.generally shownat 1, is flanged onto the manifold and to an air filter 51 communicatingwith the atmosphere. A main internal duct 26 of the pipe 1 is throttledby a throttle 2, whose arbor 3 is rotatably and controllably supportedby the pipe walls and is operatively connected to the accelerator pedal(not shown) of the vehicle. An auxiliary idling duct 4 by-passes thethrottle 2 and opens downstream of the throttle in registry with acalibrated bore 5. The duct 4 is equipped with an intercepting memberconsisting of an obturator or valve member 7 which, by an axialmovement, can have its portion 6 resting against a corresponding seat 9,thus closing the duct. The obturator 7 is driven by a solenoid 8 which,as it is energized, drives the valve member to contact the seat 9,against the bias of resilient means, not shown, which bring it back tothe at rest position shown in the drawing, when the solenoid is notenergized. The solenoid has a terminal 11 connected to ground and aterminal 10 connected, through a line 3 1, to a pole of a currentgenerator 29, whose other pole is connected to ground: on the line 31there are, serially connected, two

switches 32 and 33, respectively. The switch 32 is mechanically gangedwith the throttle 2 in the sense that it is closed when the throttlecloses the duct 26; the switch 33 is controlled by a device 28, which isconventional per se and, which receives, through a line 30, a signalwhich is a function of the rotational speed of the engine; as said speedexceeds a predetermined threshold value, above the idling value, thedevice causes the switch 33 to be closed; when the speed is below saidthreshold value, the switch is driven to opening.

As shown in FIG. 1, a fuel injecting means 43 is located within theintake duct 13 and has a fuel feed means 44 connected thereto. Aregulating means 45 is coupled to the fuel feed means 44 to regulate thefuel feed between minimum and maximum values depending on the positionof the accelerator pedal of the vehicle and on the running speed of theengine. More precisely, the regulating means 45 is connected to thethrottle 2 so as to regulate the fuel feed at the minimum or idlingvalue when the throttle is closed. A fuel feed cut-off means 41 is alsocoupled to the fuel feed means 44 to cut off the fuel feed whenelectrically energized. An electrical lead 42 connects the fuel feedcut-off means 41 to the energizing line 31.

In operation, when the accelerator pedal is released, i.e. the throttle2 is closed and the regulating means regulates the fuel feed at theminimum of idling value, and the engine rotates at the idling speed, theswitch 32 is closed but the switch 33 is open, so that the solenoid 8 isde-energized and the auxiliary duct 4 is open and keeps the air feed ata minimum or idling value; the fuel feed cut-off means 41 also isde-energized. In such a case, if the engine is accelerated, the switch-33 is closed, but the line 31 is nevertheless cut off by the opening ofthe switch 32 and the solenoid 8 is still deenergized.

Conversely, when the accelerator pedal is released but the enginerotates at a speed higher than the idling speed, the switches 32, 33 aresimultaneously closed, so that the solenoid 8 is energized and the 7closes the duct 4, thus cutting off the air feed. The fuel feed cutoffmeans 41 also are energized and entirely cut off the fuel feed, so thatneither fuel nor air are introduced into the combustion chamber 14 andthe exhaust duct 15 discharges only negligible amounts of gases, such asmay seep through an imperfect tightness of the throttle 2 and valvemember 7. It is to be noted that the switches 32 and 33 of theembodiment shown in FIG. 1 could be actuated by the same actuating meansused in the regulating means 45 to regulate the fuel feed as a functionof the position of the accelerator pedal and the engine speed.

An additional exemplary embodiment of the invention is shown in FIG. 2and parts thereof which correspond to those of the embodiment of FIG. 1have been indicated by similar reference numerals and will not beexplained in detail.

In this second embodiment, the bore 5 can be placed alternatingly incommunication either with the duct 4 i or a duct 17, according towhether a valve member 21 The valve member 21 is controlled, with theintermediary of a stem 22, by a solenoid 23 which, as it is energized,brings the valve member back to the seat 16 against the bias ofresilient means (not shown) which urges the valve member to contact theseat 20 when the solenoid 23 is not fed. A terminal 24 of the solenoidis connected to ground and a terminal 25 is connected, through a line38, to a pole of the current generator 29, whose other pole is alsoconnected to ground. On the line 38 there are, serially connected, twoswitches 39 and 40: the switch 40 is connected to the throttle 2 in thesense of being closed as the throttle is closed, while the switch 39 isconnected to a diaphragm 35 which can be deformed against the bias of acompression spring 34 and which closes the chamber 36 whichcommunicates, through a duct 37, with the manifold 12. The fuel feedcut-off means 41 also is connected to the energizing line 38 via theline 42.

In operation, when the accelerator pedal is released (or, anyhow, thethrottle 2 is closed and the regulating means 45 keeps the fuel feed atthe minimum or idling value) and the engine is driven at the idlingspeed, the switch 40 is closed but the negative pressure in the manifold12 is not sufficient to overcome the bias of the spring 34 on thediaphragm 35, so that the switch 39 remains open and the solenoid 23 isnot energized. The valve member 21 thus remains in the position of FIG.2, so that the recycling duct 19, 27, 17 is closed and the minimum oridling duct 4, 5 is open. The fuel feed cutoff means 41 also isde-energized.

As the engine is accelerated by depressing the acccelerator pedal, theswitch 40 is opened and the operation of the assembly is conventional.

When, conversely, the accelerator pedal is released but the engine isdriven at a comparatively high speed of rotation, the negative pressurein the manifold 12 is increased until overcoming the bias of the spring34, so that the switch 39 is closed and the fuel feed cut-off means 41and the solenoid 23 are energized to cut off the fuel feed and to movethe valve member 21 towards the seat 16 to cut off the idling duct 4,5.

This movement of the valve member 21 causes also the recycling duct 19,27, 17 to be opened, so that the exhaust gases are recirculated from theexhaust duct 15 to the intake duct 13 and prevent the negative pressurein the intake duct from attaining too high a value, such as to give riseto excessive seepings through the throttle 2 and valve member 21. Therecycling duct thus attains the result to improve the cut-off action ofthe fuel feed and air feed cut-off means 41 and 21. Of course, the bore5 should have an adequate size so as to prevent an excessive flow ofrecycled gas, which could lower the magnitude of the negative pressurein the manifold 12 to a value not sufficient to maintain the switch 39closed. It is also important to notice that the recycling of hot exhaustgases allows a flow of gas in the engine, when no combustion occurs,without experiencing too intensive a cooling of the combustion chamber,whose consequence would be the emission of unburned fractions as theengine resumes its normal operation.

The embodiments shown in the drawings are, as outlined above, mereexamples and many modifications can be provided for without therebydeparting from the scope of the present invention. More particularly,the control circuits for the solenoid as illustrated can beindifferently applied to either embodiment described herein.

What is claimed is: r

1. An internal combustion engine of the fuel injection type, comprisinga combustion chamber, an intake duct leading to said chamber, fuelinjecting means located in said intake duct, fuel feed means connectedto said fuel injecting means, regulating means coupled to said fuel feedmeans to regulate the fuel feed, air feed means for introducing air inthe intake duct upstream to the fuel injecting means, throttling meanscoupled to said air feed means to regulate the air feed concurrentlywith the operation of said regulating means, fuel feed cut-off means,air feed cut-off means and control means responsive to the concurrentoperation of said regulating means and said throttling means and to theengine speed to actuate the fuel feed and air feed cutoff means to cutoff the fuel feed and the air feed when said regulating means and saidthrottling means are arranged to regulate the fuel feed and the air feedat the idling values and the engine speed is higher than the idlingspeed, the air feed means comprising a main duct in which saidthrottling means is arranged and an auxiliary duct in paralleltherewith, said air feed cut-off means being defined by a valve memberwhich is actuated to close said auxiliary dluct when the throttlingmeans closes said main duct and the engine speed is higher than theidling speed, and wherein the combustion chamber is provided with anexhaust duct which is connected to the intake duct via a recycling ductprovided with gas recycling cut-off means which normally closes saidrecycling duct and which is controlled to open said recycling duct whensaid air feed cut-off means is actuated.

2. The internal combustion engine as claimed in claim 1, in which saidvalve member is controlled by an electromagnet so as to be moved to theclosing position when the electromagnet is energized.

3. The internal combustion engine as claimed in claim 2, in which saidelectromagnetis fed by a current generator through a line on which thereare, serially arranged, a first switch and a second switch, the firstswitch being connected to the throttling means so as to be closed whenthe throttling means close said main duct, and the second switch beingcontrolled by a device sensitive to the engine speed so as to be closedwhen said speed exceeds the idling value.

1. An internal combustion engine of the fuel injection type, comprisinga combustion chamber, an intake duct leading to said chamber, fuelinjecting means located in said intake duct, fuel feed means connectedto said fuel injecting means, regulating means coupled to said fuel feedmeans to regulate the fuel feed, air feed means for introducing air inthe intake duct upstream to the fuel injecting means, throttling meanscoupled to said air feed means to regulate the air feed concurrentlywith the operation of said regulating means, fuel feed cut-off means,air feed cut-off means and control means responsive to the concurrentoperation of said regulating means and said throttling means and to theengine speed to actuate the fuel feed and air feed cut-off means to cutoff the fuel feed and the air feed when said regulating means and saidthrottling means are arranged to regulate the fuel feed and the air feedat the idling values and the engine speed is higher than the idlingspeed, the air feed means comprising a main duct in which saidthrottling means is arranged and an auxiliary duct in paralleltherewith, said air feed cut-off means bEing defined by a valve memberwhich is actuated to close said auxiliary duct when the throttling meanscloses said main duct and the engine speed is higher than the idlingspeed, and wherein the combustion chamber is provided with an exhaustduct which is connected to the intake duct via a recycling duct providedwith gas recycling cut-off means which normally closes said recyclingduct and which is controlled to open said recycling duct when said airfeed cut-off means is actuated.
 2. The internal combustion engine asclaimed in claim 1, in which said valve member is controlled by anelectromagnet so as to be moved to the closing position when theelectromagnet is energized.
 3. The internal combustion engine as claimedin claim 2, in which said electromagnet is fed by a current generatorthrough a line on which there are, serially arranged, a first switch anda second switch, the first switch being connected to the throttlingmeans so as to be closed when the throttling means close said main duct,and the second switch being controlled by a device sensitive to theengine speed so as to be closed when said speed exceeds the idlingvalue.